The present invention relates to a weaving method for in-plane multiaxial thick woven fabrics which are effectively used for interior and exterior materials of aircraft and the like.
Conventionally, glass fiber woven fabrics which are impregnated with thermosetting resin, reinforced resin parts which are formed by laminating carbon fiber woven fabrics in multiple layers and by heating and curing, and composite material parts have been used for interior and exterior materials of aircraft and in other various industrial fields because they are light in weight and have high mechanical strength. In the case where this material is used for the external surface of aircraft shell or the like, there is a problem in that separation occurs when a stone or the like strikes the external surface when the aircraft runs on the ground.
To solve this problem, a three-dimensional woven fabric for reinforcing a structure, in which layers of woven fabric are integrally connected by using knotting thread, has been disclosed in Japanese Patent Publication No. 13060/1990.
The three-dimensional woven fabric disclosed in Japanese Patent Publication No. 13060/1990 will be described with reference to FIGS. 17 and 18. In these figures, reference numerals 50, 50a to 50c denote warps, 51, 51a to 51d denote wefts, and 52a and 52b denote knotting threads. This three-dimensional woven fabric is woven with a weaving machine. As shown in FIG. 17, wefts 51a to 51d are laminated in parallel, warps 50a to 50c are laminated perpendicular to the wefts, and knotting threads 52a and 52b fix internal warps 50a to 50c and wefts 51b and 51c by turning at the outside wefts 51a and 51d.
As described above, conventional composite material parts in which woven fabric impregnated with thermosetting resin is laminated and heated for formation has a disadvantage that the laminated woven fabric is separated by a shock due to collision from the outside.
With the three-dimensional woven fabric shown in FIGS. 17 and 18, in which laminated warp layer and weft layer are connected by knotting threads 52a and 52b, separation occurring in composite material parts, in which woven fabric impregnated with thermosetting resin is laminated and heated for curing, does not occur. In this woven fabric, however, fibers cannot be arranged in a multiaxial mode in a plane, there being a problem in that fiber arrangement for lightweight and optimized mechanical strength cannot be set.
To solve the above problem, Japanese Patent Application No. 157513/1988 discloses a method in which triaxial or quadaxial woven fabric with simple structure can be formed by a weft insertion device and a beating-up device by crossing a diagonal warp supplied from a creel for diagonal warp and a diagonal warp of opposite direction alternately in the reverse inclined direction and then by appropriately shedding after transforming to substantially right angles. However, this method can weave only thin in-plane multiaxial woven fabrics. In this case, as described in the prior art, a problem of separation is posed because a laminating operation is required. Also, there is a problem in that the prior art cannot obtain in-plane multiaxial thick woven fabrics.